Not applicable.
Not applicable.
This invention relates to a filter system, and more specifically, to a backwashable filter system of the type utilized in petroleum refining applications.
Filter assemblies employing an array of individual filter stalks have long been utilized. Unfiltered fluid enters the filter assembly, passes through one of the slotted or perforated filter stalks arranged within the filter assembly, and exits the filter assembly as a filtered fluid. Solid contaminants are retained on the outer surface of the filter stalks as the fluid passes through the stalks. As more contaminants are retained against the filter stalks, the differential pressure across the filter medium increases and consequentially the flow decreases.
One method of cleaning filter stalks is a process known as backwashing. During backwashing, a cleaning fluid is forced through the filter assembly in a direction opposite to the normal operating flow. Backwashing alone, however, is of limited effectiveness. Even when a large amount of backwash fluid or an extended period of time are used, simple backwashing may clean only a portion of the filter stalks effectively.
To address this drawback, devices to supplement and enhance the backwashing process have been introduced. One such device is disclosed in U.S. Pat. No. 3,387,712, issued to Schrink. This patent discloses a backwash water diffuser for use within a filter stalk. The diffuser is made up of a shaft that extends the length of the filter stalk and that has a number of diffuser lugs mounted thereon. The diffuser lugs have an annular frusto-conical surface which faces the direction that the backwash fluid enters the filter, and, at least in one embodiment, are located within the seventy percent of the filter stalk adjacent to the backwash water inlet.
The present applicants have found that a rod which is mounted within a filter stalk and which has deflector disks that have a surface perpendicular to the rod and that are spaced along the rod enhances the backwashing action and, therefore, enhances cleaning of the filter stalk. The increased backwashing action results from the diversionary effect of the deflector disks and better distribution of the backwash fluid up and down the stalk. The result is improved removal of contaminants. In addition, applicants have found that the efficiency of the backwash process is enhanced when a diffuser plate that has apertures for the passage of fluid is mounted above the individual filter stalks.
Accordingly, it is the object of this invention to provide a diffuser rod with deflector disks rigidly mounted on said rod for use in a filter stalk to deflect liquid radially during the backwash process.
It is a further object of this invention to provide a backwashable filter assembly containing a number of filter stalks with each filter stalk including a diffuser rod as described above.
It is a further object of this invention to provide a backwashable filter assembly containing a diffuser plate that is located within the filter assembly at the end where the backwash liquid enters the filter assembly and is spaced from the filter stalks and that has a number of apertures corresponding to the number of filter stalks present within the filter assembly.
Finally, it is a further object of this invention to provide a method of backwashing a filter assembly that includes the step of introducing a diffuser rod and a diffuser plate to the filter assembly.
Further objects of this invention will be apparent to persons knowledgeable with devices of this general type upon reading the following description and examining the accompanying drawings.
A diffuser rod for use in a filter stalk, said rod having deflector disks rigidly mounted thereon to deflect liquid radially during the backwash process, is disclosed. A backwashable filter assembly containing a diffuser plate that is located within the filter assembly at the end where the backwash fluid enters the filter assembly and a number of filter stalks with each filter stalk including a diffuser rod is disclosed. Finally, a method of backwashing a filter assembly that includes the step of introducing a diffuser rod and a diffuser plate to the filter assembly is disclosed.